swtpm: Display the --print-states capability and document it

Display the --print-states capability in the --print-capabilites
output as cmdarg-print-states.

Document availability in the man page.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

man/man8/swtpm.pod

@@ -304,6 +304,7 @@ may contain the following:
         "cmdarg-seccomp",
         "cmdarg-key-fd",
         "cmdarg-pwd-fd",
+        "cmdarg-print-states",
         "nvram-backend-dir",
         "nvram-backend-file",
         "tpm-send-command-header",
@@ -347,6 +348,10 @@ The I<--key> option supports the I<fd=> parameter.
 
 The I<--key> option supports the I<pwdfd=> parameter.
 
+=item B<cmdarg-print-states>
+
+The I<--print-states> option is supported.
+
 =item B<nvram-backend-dir>
 
 The I<--tpmstate> option supports the I<backend-uri=dir://...> and
@@ -370,6 +375,30 @@ rsa-keysize verbs is shown then only RSA 2048 bit keys are supported.
 
 =back
 
+=item B<--print-states>
+
+This option allows to print out the TPM 1.2 or TPM 2 state blobs
+that are currently stored in a storage backend. This option requires
+that the storage backend be specified using the I<--tpmstate> option
+and if TPM 2 state blobs are supposed to be shown, the I<--tpm2>
+option must be passed.
+
+The following shows the JSON output of this option. It indicates that
+the 'permall' and 'volatile' states are available.
+
+    {
+      "type": "swtpm",
+      "states": [
+        {
+          "name": "permall",
+          "size": 6013
+        }, {
+          "name": "volatile",
+          "size": 1087
+        }
+      ]
+    }
+
 =item B<-h|--help>
 
 Display usage info.

src/swtpm/capabilities.c

@@ -143,7 +143,7 @@ int capabilities_print_json(bool cusetpm)
          "{ "
          "\"type\": \"swtpm\", "
          "\"features\": [ "
-             "%s%s%s%s%s%s%s%s%s%s"
+             "%s%s%s%s%s%s%s%s%s%s%s"
           " ], "
          "\"version\": \"" VERSION "\" "
          "}",
@@ -154,6 +154,7 @@ int capabilities_print_json(bool cusetpm)
          cmdarg_seccomp,
          true         ? "\"cmdarg-key-fd\", "          : "",
          true         ? "\"cmdarg-pwd-fd\", "          : "",
+         true         ? "\"cmdarg-print-states\", "    : "",
          nvram_backend_dir,
          nvram_backend_file,
          keysizecaps  ? keysizecaps                    : ""

tests/_test_print_capabilities

@@ -25,7 +25,7 @@ if [ "${SWTPM_IFACE}" != "cuse" ]; then
 	noncuse='"tpm-send-command-header", "flags-opt-startup", '
 fi
 
-exp='\{ "type": "swtpm", "features": \[ "tpm-1.2",( "tpm-2.0",)? '${noncuse}${seccomp}'"cmdarg-key-fd", "cmdarg-pwd-fd", "nvram-backend-dir", "nvram-backend-file" \], "version": "[^"]*" \}'
+exp='\{ "type": "swtpm", "features": \[ "tpm-1.2",( "tpm-2.0",)? '${noncuse}${seccomp}'"cmdarg-key-fd", "cmdarg-pwd-fd", "cmdarg-print-states", "nvram-backend-dir", "nvram-backend-file" \], "version": "[^"]*" \}'
 if ! [[ ${msg} =~ ${exp} ]]; then
 	echo "Unexpected response from ${SWTPM_IFACE} TPM to --print-capabilities:"
 	echo "Actual   : ${msg}"

tests/_test_tpm2_print_capabilities

@@ -26,7 +26,7 @@ if [ "${SWTPM_IFACE}" != "cuse" ]; then
 fi
 
 # The rsa key size reporting is variable, so use a regex
-exp='\{ "type": "swtpm", "features": \[( "tpm-1.2",)? "tpm-2.0", '${noncuse}${seccomp}'"cmdarg-key-fd", "cmdarg-pwd-fd", "nvram-backend-dir", "nvram-backend-file"(, "rsa-keysize-1024")?(, "rsa-keysize-2048")?(, "rsa-keysize-3072")? \], "version": "[^"]*" \}'
+exp='\{ "type": "swtpm", "features": \[( "tpm-1.2",)? "tpm-2.0", '${noncuse}${seccomp}'"cmdarg-key-fd", "cmdarg-pwd-fd", "cmdarg-print-states", "nvram-backend-dir", "nvram-backend-file"(, "rsa-keysize-1024")?(, "rsa-keysize-2048")?(, "rsa-keysize-3072")? \], "version": "[^"]*" \}'
 if ! [[ ${msg} =~ ${exp} ]]; then
 	echo "Unexpected response from ${SWTPM_IFACE} TPM to --print-capabilities:"
 	echo "Actual   : ${msg}"